Beta-alanine as a sport supplement

Within the past few years, beta-alanine has appeared on the sport nutrition market. Beta-alanine is typically administered as capsules or as a powder that is mixed with a liquid (usually water). While several clinical trials have shown increases in markers of aerobic endurance performance, body composition, and strength with beta-alanine, others have demonstrated no ergogenic benefits. This section discusses beta-alanine as a sport supplement, beginning with its parent compound carnosine.

Carnosine is a dipeptide composed of the amino acids histidine and beta-alanine. Carnosine occurs naturally in the brain, cardiac muscle, kidney, and stomach, as well as in relatively large amounts in skeletal muscles (primarily Type II muscle fibers). These Type II muscle fibers are the fast-twitch muscle fibers used in explosive movements like those in weight training and sprinting. Interestingly, athletes whose performance demands extensive anaerobic output have higher concentrations of carnosine.

Carnosine contributes to the buffering of hydrogen ions, thus attenuating (slowing down) a drop in pH associated with anaerobic metabolism. Carnosine is very effective at buffering the hydrogen ions responsible for producing the ill effects of lactic acid. Carnosine is believed to be one of the primary muscle buffering substances available in skeletal muscle. In theory, if carnosine could attenuate the drop in pH noted with high-intensity exercise, one could possibly exercise at high intensities for a longer duration. Relative to ingestion, however, carnosine is rapidly degraded into beta-alanine and histidine as soon as it enters the blood through the activity of the enzyme carnosinase. Thus there is no advantage to ingesting carnosine. However, independent ingestion of beta-alanine and histidine allows these two compounds to be transported into the skeletal muscle and to be resynthesized into carnosine. It appears that beta-alanine is the amino acid that most influences intramuscular carnosine levels because it is the rate-limiting substrate in this chemical reaction (Dunnett and Harris 1999). In fact, studies have demonstrated that 28 days of beta-alanine supplementation at a dosage of 4 to 6 g/day resulted in an increase of intramuscular levels of carnosine by approximately 60% (Harris et al. 2005; Zoeller et al. 2007).

Researchers have begun extensive research in the area of beta-alanine supplementation for strength athletes. Stout and colleagues (2006) examined the effects of beta-alanine supplementation on physical working capacity at fatigue threshold (PWCFT) in untrained young men. The participants ingested 6.4 g of beta-alanine for six days followed by 3.2 g for three weeks. The results revealed a significantly greater increase in PWCFT in the beta-alanine as compared to the placebo group. Stout and colleagues (2008) then investigated the effects of 90 days of beta-alanine supplementation (2.4 g/day) on the PWCFT in elderly men and women. They found significant increases in PWCFT (28.6%) from pre- to postsupplementation for the beta-alanine treatment group but no change with the placebo treatment. In a study using collegiate American football players, Hoffman and colleagues (2008a) found that subjects supplementing with beta-alanine (4.5 g) increased training volume significantly over 30 days compared to subjects taking a placebo. Elsewhere, Hoffman and associates (2008b) investigated the effect of 30 days of beta-alanine supplementation (4.8 g/day) on resistance exercise performance and endocrine changes in resistance-trained men. The beta-alanine group experienced a significant 22% increase in total number of repetitions as compared to the placebo group at the end of the four-week intervention. There were no significant differences between groups in hormonal responses.

physical working capacity at fatigue threshold (PWCFT)—This parameter, often obtained using a cycle ergometer test, can identify the power output at the neuromuscular fatigue threshold.

Several studies have investigated the effects of supplementing creatine and beta-alanine together (Stout et al. 2006; Zoeller et al. 2007; Hoffman et al. 2006). The proposed benefit would increase work capacity and increase time to fatigue. Hoffman and colleagues (2006) studied the effects of creatine (10.5 g/day) plus beta-alanine (3.2 g/day) on strength, power, body composition, and endocrine changes as collegiate American football players underwent a 10-week resistance training program. Results demonstrated that creatine plus beta-alanine was effective at enhancing strength performance. Creatine plus beta-alanine supplementation also appeared to have a greater effect on lean tissue accruement and body fat composition than creatine alone. However, Stout and colleagues (2006) found that creatine did not appear to have an additive effect over beta-alanine alone.

While many studies have highlighted the positive results of beta-alanine supplementation, several other investigations have shown no improvements. In the study of collegiate American football players already mentioned, Hoffman and colleagues (2008a) examined the effects of 30 days of beta-alanine supplementation (4.5 g/day) on anaerobic performance measures. Supplementation began three weeks before preseason football training camp and continued for an additional nine days during camp. Results showed a trend toward lower fatigue rates during 60 seconds of maximal exercise; however, three weeks of beta-alanine supplementation did not result in significant improvements in fatigue rates during high-intensity anaerobic exercise. Elsewhere, Kendrick and colleagues (2008) assessed whole-body muscular strength and changes in body composition after 10 weeks of beta-alanine supplementation at a dosage of 6.4 g/day. Participants included 26 healthy male Vietnamese physical education students who were not currently involved in any resistance training program. The authors reported no significant differences between the beta-alanine group and a placebo group in whole-body strength and body composition measures after 10 weeks of supplementation.

Beta-alanine supplementation is relatively new and is a potentially useful ergogenic aid. It is important to realize that there have been only a few well-designed clinical investigations on this compound, and the published results to date have been equivocal. One of the potential limitations in the existing literature is the inconsistencies in dosing regimens. While much of the research has been positive, the dosing regimens have varied from 3 to 6 g/day. This problem is confounded by the fact that the higher doses were less effective in some cases. In relation to side effects and dosage, research from Harris and colleagues (2006) has revealed that relatively high single doses of beta-alanine are responsible for unpleasant symptoms of paresthesia (tingling sensation in the skin) that may last up to an hour. This sensation can be eliminated if the maximum single dose is 10 mg/kg of body weight, which corresponds to an average of 800 mg of beta-alanine in a single dose (Harris et al. 2006).

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